Near-bit multi-parameter downhole measurement and control system while drilling

ABSTRACT

A near-bit multi-parameter downhole measurement and control system while drilling, including a ground device and a downhole assembly. The downhole assembly includes a drill bit, a multi-parameter acquisition and signal transmission sub, a positive displacement motor or drilling tool, a receiving and transmitting module, a wireless communication sub, and a non-magnetic drill collar which are connected in sequence. The multi-parameter acquisition and signal transmission sub is provided with the near-bit measuring instrument. The receiving and transmitting module is configured to receive signals from the near-bit measuring instrument and transmit the signals to the wireless communication sub. The wireless communication sub is configured to transmit the received signals to the ground device through a mud pulse generator in a form of pulse signal, and the ground device decodes and analyzes downhole data. The system can monitor and adjust the real-time changes of downhole engineering parameters timely.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/CN2022/106152, filed on Jul. 18, 2022, which claims the benefitof priority from Chinese Patent Application No. 202111230883.1, filed onOct. 22, 2021. The contents of the aforementioned application, includingany intervening amendments thereto, are incorporated herein by referencein its entirety.

TECHNICAL FIELD

The disclosure relates to the field of downhole data wirelessmeasurement while drilling in drilling engineering, in particular to anear-bit multi-parameter downhole measurement and control system whiledrilling.

BACKGROUND

With the development of drilling technology, a near-bit measurement andcontrol system while drilling has been developed in order to furtherimprove the drilling efficiency and oil and gas recovery of deep wells,ultra-deep wells and horizontal wells with long displacement. Most ofthe existing measurement while drilling systems cannot solvesimultaneously the measurement problems of a set of engineeringparameters such as bottom hole temperature, internal and externalannular pressure, triaxial vibrations, weight on bit, torque, rotationand bending moment, and the drilling efficiency is relatively slow.

SUMMARY

In order to solve the above technical problems, the disclosure providesa near-bit multi-parameter downhole measurement and control system whiledrilling, which can monitor the real-time changes of downholeengineering parameters in real-time, and adjust the drilling parameterssuch as weight on bit, rotation rate, torque, and drilling fluidperformance during drilling process according to the changes of downholeparameters, As a result, the evaluation of drilling efficiency is notscientific and it is difficult to identify downhole complex situationsin time.

A near-bit multi-parameter downhole measurement and control system whiledrilling, comprising a ground device and a downhole assembly.

The downhole assembly comprises a drill bit, a multi-parameteracquisition and signal transmission sub, a positive placement motor or adrill tool, a fishing joint, a receiving and transmitting module, afirst connector, a wireless communication sub, a second connector and anon-magnetic drill collar which are connected in sequence.

The multi-parameter acquisition and signal transmission sub comprises afirst drill collar, a power supply arranged on the first drill collar, adata processing circuit, a near-bit measuring instrument, a transmissionantenna designed using vertical electric field method, an insulatingring and a data storage module; the near-bit measuring instrument isarranged on the first drill collar near the drill bit, and comprises atorque strain gauge, a weight on bit strain gauge, a pressure sensor, atemperature sensor, a triaxial accelerometer, and a circuit board; thenear-bit measuring instrument is configured for data acquisitionaccording to a preset time interval, and stores the acquisition data tothe data storage module and transmits them to the data processingcircuit; the data processing circuit is connected with the transmissionantenna in communication connection; and the transmission antenna isconfigured to transmit signals to the receiving and transmitting module.

The receiving and transmitting module is configured to receive signalsfrom the transmission antenna and transmit the signals to the wirelesscommunication sub.

The wireless communication sub is configured to transmit the receivedsignals to the ground device through a mud pulse generator in a form ofpulse signals, and the ground device decodes and analyzes downhole data.

Further, a set of holes are provided on the first drill collar near aposition of the drill bit, and the hole is configured for installing thenear-bit measuring sensors.

Further, the measuring sensor like the torque strain gauge, the weighton bit strain gauge, the pressure sensor, the temperature sensor, thetriaxial accelerometer, and the circuit board are arranged in the aboveholes respectively.

Further, an electromagnetic coupling transmission device is arrangedinside the first connector and the second connector; the first connectoris configured to achieve a transmission of electrical energy and datasignals between the receiving and transmitting module and the wirelesscommunication sub; and the second connector is configured to achieve atransmission of electrical energy and data signals between the wirelesscommunication sub and the non-magnetic drill collar.

Further, a MWD measuring sub is provided inside the wirelesscommunication sub, and data measured by the MWD measuring sub arecollected and transmitted to the ground device by the wirelesscommunication sub.

The advantageous effects: Compared with the prior art, the disclosurehas the following technical effects:

The near-bit multi-parameter downhole measurement and control systemwhile drilling can monitor the downhole engineering parameters inreal-time such as torque, weight on bit, bending moment, temperature,pressure inside and outside drill string, rotation rate, and triaxialvibration. And the measurement position is closer to the drill bit,making the measurement data more realistic and accurate, such that itcan monitor the real-time changes of downhole engineering parameters ,and timely and accurately predict whether there are complicated downholesituations such as well kick, lost circulation, pipe sticking anddrilling tools damage, which can greatly reduce the non-drilling timeand improve the drilling efficiency.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 and FIG. 11 are schematic diagrams of the structure of a near-bitmulti-parameter downhole measurement and control system while drilling;

FIG. 2 is a schematic diagram of the effect of the length of themulti-parameter acquisition and signal transmission sub on the wellpathdeviation rate under certain operating conditions;

FIG. 3 is a schematic diagram of the effect of the length of themulti-parameter acquisition and signal transmission sub on the drill bitoffset under certain operating conditions;

FIG. 4 is a schematic diagram of the multi-parameter acquisition andsignal transmission sub;

FIG. 5 is a cross-sectional schematic diagram of the multi-parameteracquisition and signal transmission sub;

FIG. 6 is a cross-sectional view at A-A in FIG. 5 ;

FIG. 7 is a cross-sectional view at B-B in FIG. 5 ;

FIG. 8 is a cross-sectional schematic diagram of the wirelesscommunication sub;

FIG. 9 is a cross-sectional schematic diagram of the first connector;

FIG. 10 is a cross-sectional schematic diagram of the second connector;

FIG. 12 is a physical diagram of an electromagnetic couplingtransmission device.

Number references in the drawings: 1—drill bit; 2—multi-parameteracquisition and signal transmission sub; 21—hole; 3—screw power drilltool; 4—fishing joint; 5—receiving and transmitting module; 6—firstconnector; 7—wireless communication sub; 8—second connector;9—non-magnetic drill collar; 10—ground device; 20—downhole assembly;201—first drill collar; 22—power supply; 23—data processing circuit;24—near-bit measuring instrument; 25—transmission antenna; 26—insulationring; 27—data storage module; 241—torque strain gauge; 242—WOB (WeightOn Bit) strain gauge; 243—pressure sensor; 244—temperature sensor;245—triaxial accelerometer; 246—circuit board; 61—electromagneticcoupling transmission device; 71—mud pulse generator; 72—MWD measuringsub.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As shown in FIGS. 1, 4-7, and 10 , a near-bit multi-parameter downholemeasurement and control system while drilling is provided, whichincludes a ground device 10 and a downhole assembly 20.

Specifically, the ground device 10 includes a pressure sensor, awireless transceiver host, a wireless sensor host, a driller display,and a data processing instrument.

As shown in FIGS. 1-10 , the downhole assembly 20 includes a drill bit1, a multi-parameter acquisition and signal transmission sub 2, a screwpower drill tool 3, a fishing joint 4, a receiving and transmittingmodule 5, a first connector 6, a wireless communication sub 7, a secondconnector 8 and a non-magnetic drill collar 9 which are connected insequence.

Wherein, the multi-parameter acquisition and signal transmission sub 2includes a first drill collar 201, a power supply 22 arranged on thefirst drill collar 201, a data processing circuit 23, a near-bitmeasuring instrument 24, a transmission antenna 25 designed usingvertical electric field method, an insulating ring 26 and a data storagemodule 27.

More specifically, the near-bit measuring instrument 24 is arranged onthe first drill collar 201 near the drill bit 1, which includes a torquestrain gauge 241, a weight on bit strain gauge 242, a pressure sensor243, a temperature sensor 244, a triaxial accelerometer 245, and acircuit board 246. The near-bit measuring instrument 24 is configured tocollect data according to a preset time interval, and stores thecollected data to the data storage module 27 and transmits the collecteddata to the data processing circuit 23. The data processing circuit 23is connected with the transmission antenna 25 in communicationconnection, and the transmission antenna 25 is configured to transmitsignals to the receiving and transmitting module 5. The receiving andtransmitting module 5 is configured to receive signals from thetransmission antenna 25 and transmit the signals to the wirelesscommunication sub 7. The wireless communication sub 7 is configured totransmit the received signals to the ground device 10 through a mudpulse generator 71 in a form of pulse signal, and the ground device 10decodes and analyzes downhole data.

First of all, the near-bit measuring instrument 24 includes the torquestrain gauge 241, the weight on bit strain gauge 242, the pressuresensor 243, the temperature sensor 244, the triaxial accelerometer 245,and the circuit board 246 which is connected with the above instrumentsthrough electrical signals. In this way, it can measure parameters suchas weight on bit, bending moment, temperature, inner and outer ringpressure, triaxial vibration, etc. during drilling. The measuredparameters are more abundant, which can greatly improve the drillingefficiency.

Secondly, by setting the near-bit measuring instrument 24 set at themulti-parameter acquisition and signal transmission sub 2 and locatednear the drill bit 1, it has at least two advantages:

On the one hand, due to the parameter measurement position close to thedrill bit 1, its measurement data is closer to the drilling operationposition and more accurate.

On the other hand, the aforementioned measuring instruments set on themulti-parameter acquisition and signal transmission sub 2 can controlthe length of the multi-parameter acquisition and signal transmissionsub 2 within 1.2 m, effectively ensuring the deflection rate near thedrill bit 1 and reducing the impact of the multi-parameter acquisitionand signal transmission sub 2 on the offset of the drill bit 1 duringdrilling. The details are as follows:

Due to the significant impact of the position of the multi-parameteracquisition and signal transmission sub 2 on the deflection rate of thesingle bend screw drill tool, the deflection rate will decrease due tothe length distance between the position of the multi-parameteracquisition and signal transmission sub 2 and the drill bit 1, and mayeven lose the deflecting capacity at a long distance.

As shown in FIGS. 2-3 , FIG. 2 shows the relationship between the lengthof the multi-parameter acquisition and signal transmission sub 2 and thewellpath deviation rate under certain operating conditions; FIG. 3 showsthe relationship between the length of the multi-parameter acquisitionand signal transmission sub 2 and the offset distance of the drill bit 1under certain operating conditions.

Wherein, the certain operating conditions refer to:

1. Bottom hole assembly (BHA): the drill bit 1 has a diameter of 215.9mm and a length of 0.25 m, the positive displacement motor 3 has adiameter of 172 mm and a total length of 7.95 m, with bending angles of1.0° and −1.5°. The bending angles are 1.4 m away from the end face ofdrill bit 1, and the center position of the multi-parameter acquisitionand signal transmission sub 2 is 0.6 m away from the end face of thedrill bit 1.

2. Drilling parameters and wellbore conditions: drilling pressure is 60kN, wellbore inclination angle is 45°, anisotropy index of the drill bit1 is 0.05, specific gravity of drilling fluid is 1.25, formationinclination angle is 5°, and formation anisotropy index is 0.99.

From FIG. 1 and FIG. 2 , it can be clearly seen that the position andlength of the multi-parameter acquisition and signal transmission sub 2have a significant impact on the deflection rate of the single bendscrew drill tool. The deflection rate will rapidly decrease as theposition of the multi-parameter acquisition and signal transmission sub2 becomes farther away, and even lose its deviation build-up capacity.Moreover, when the length of the multi-parameter acquisition and signaltransmission sub 2 is 1.2 m or less, the effect of the multi-parameteracquisition and signal transmission sub 2 on the increment of deviationbuild-up rate is better.

Furthermore, referring to FIG. 4 to FIG. 7 , in some embodiments, a hole21 is provided on the first drill collar 201 near the position of thedrill bit 1, and the hole 21 is configured for setting the near-bitmeasuring instrument 24. By setting the near-bit measuring instrument 24in the hole 21 of the first drill collar 201, the near-bit measuringinstrument 24 can be hidden in the side wall of the first drill collar201. During the drilling operation of the drill bit 1, there is littlefriction between the near-bit measuring sut 24 and the wellbore wall,thereby improving the detection accuracy of various downhole measurementdata.

Further, as shown in FIG. 4 to FIG. 6 , in some embodiments, a number ofthe holes 21 are provided, and the torque strain gauge 241, the weighton bit strain gauge 242, the pressure sensor 243, the temperature sensor244, the triaxial accelerometer 245, and the circuit board 246 arearranged in each hole 21 respectively. In this way, the assembly of eachmeasuring instrument is convenient.

Referring to FIG. 9 , FIG. 10 and FIG. 12 , in some embodiments, boththe first connector 6 and the second connector 8 are internally equippedwith an electromagnetic coupling transmission device 61. Theelectromagnetic coupling transmission device 61 includes a outer ring ofcopper ring and an electromagnetic coil arranged inside the outer ringof copper ring. The first connector 6 is used to achieve thetransmission of electrical energy and data signals between the receivingand transmitting module 5 and the wireless communication sub 7. Thesecond connector 8 is used to achieve the transmission of electricalenergy and data signals between the wireless communication sub 7 and thenon-magnetic drill collar 9.

By setting the electromagnetic coupling transmission device 61 in thefirst connector 6 and the second connector 8, it can achieve synchronoustransmission of electrical energy and data signals through the wirelesstransmission technology of magnetic coupling resonance while connectingthe receiving and transmitting module 5 to the wireless communicationsub 7, as well as the wireless communication sub 7 to the non-magneticdrill collar 9.

Referring to FIG. 8 , in some embodiments, a MWD(measurement-while-drilling) measuring sub 72 is provided inside thewireless communication sub 7, the wireless communication sub 7 collectsdata measured by the MWD measuring sub 72 and transmits it to the grounddevice 10 in the form of a pulse signal through the mud pulse generator71.

In addition to the MWD measuring sub 72, the wireless communication sub7 is also equipped with a signal receiving device, a main controlcircuit, a signal encoding circuit, and the mud pulse generator 71.After receiving data, the main control circuit is used to store thedata.

Specifically, a signal processing circuit and a signal transmissiondevice for the drill bit 1 system are installed in the wirelesscommunication sub 7, which is used to transmit the preprocessed signalthrough the second connector 8 to the non-magnetic drill collar 9through electromagnetic wave wireless short transmission. The data isstored by the main control circuit in the non-magnetic drill collar 9,and then controlled by the mud pulse driving circuit to transmit thepulse signal to the ground device 10 through the mud pulse generator 71.

Due to the traditional wireless short transmission technology with atransmission rate of 50 bit/s, the transmission speed from MWD mud pulsegenerator 71 to the ground device 10 is 1 bit/s. There is a significantdifference in the transmission rate between the two, and thetransmission bandwidth of MWD mud pulse generator is small, resulting inthe inability of the multi-parameter acquisition and signal transmissionsub 2 to directly transmit signals to the main control system of MWDthrough wireless short transmission technology. Therefore, it isnecessary to transform the data into a data transmission sequence thatadapts to the mud pulse transmission speed. For this purpose, the signalof the multi-parameter acquisition and signal transmission sub 2 ispre-stored through the wireless communication sub 7. At the same time,the wireless communication sub 7 compresses the signal quantity,processes the detected parameter signal according to the instructions ofthe ground device 10, and transmits it to the signal encoding circuit.Finally, the mud pulse driving circuit controls the mud pulse generator71 to transmit the pulse signal to the ground device 10, and then theground device 10 receives and decodes downhole data to achieve real-timetransmission of downhole data to the ground.

What is claimed is:
 1. A near-bit multi-parameter downhole measurementand control system while drilling, comprising a ground device and adownhole assembly, wherein the downhole assembly comprises a drill bit,a multi-parameter acquisition and signal transmission sub, a screw powerdrill tool, a fishing joint, a receiving and transmitting module, afirst connector, a wireless communication sub, a second connector and anon-magnetic drill collar which are connected in sequence; themulti-parameter acquisition and signal transmission sub comprises afirst drill collar, a power supply arranged on the first drill collar, adata processing circuit, a near-bit measuring instrument, a transmissionantenna designed using vertical electric field method, an insulatingring and a data storage module; the near-bit measuring instrument isarranged on the first drill collar near the drill bit, and comprises atorque strain gauge, a weight on bit strain gauge, a pressure sensor, atemperature sensor, a triaxial accelerometer, and a circuit board; thenear-bit measuring instrument is configured for data acquisitionaccording to a preset time interval, and stores the collected data tothe data storage module and transmits them to the data processingcircuit; the data processing circuit is connected with the transmissionantenna in communication connection; and the transmission antenna isconfigured to transmit signals to the receiving and transmitting module;the receiving and transmitting module is configured to receive signalsfrom the transmission antenna and transmit the signals to the wirelesscommunication sub; and the wireless communication sub is configured totransmit the received signals to the ground device through a mud pulsegenerator in a form of pulse signal, and the ground device decodes andanalyzes downhole data.
 2. The near-bit multi-parameter downholemeasurement and control system while drilling according to claim 1,wherein a number of holes are provided on the first drill collar near aposition of the drill bit, and the hole are configured for setting thenear-bit measuring instruments.
 3. The near-bit multi-parameter downholemeasurement and control system while drilling according to claim 2,wherein the hole are provided for installing sensors such as torquestrain gauge, the weight on bit strain gauge, the pressure sensor, thetemperature sensor, the triaxial accelerometer, and the circuit boardcorrespondingly
 4. The near-bit multi-parameter downhole measurement andcontrol system while drilling according to claim 1, wherein anelectromagnetic coupling transmission device is arranged inside thefirst connector and the second connector; the first connector isconfigured to achieve a transmission of electrical energy and datasignals between the receiving and transmitting module and the wirelesscommunication sub; and the second connector is configured to achieve atransmission of electrical energy and data signals between the wirelesscommunication sub and the non-magnetic drill collar.
 5. The near-bitmulti-parameter downhole measurement and control system while drillingaccording to claim 1, wherein a MWD measuring sub is provided inside thewireless communication sub, and data measured by the MWD measuring subare collected and transmitted to the ground device by the wirelesscommunication sub.